1. Field of the Invention
Aspects of the present invention relate to a circuit connection control system of a fuel cell and a method of operating the same, and more particularly, to a circuit connection control system that facilitates electrical connection between cells and a method of operating the same.
2. Description of the Related Art
In a monopolar type fuel cell, a plurality of cells are formed on an electrolyte membrane, with a plurality of anodes on one side of the electrolyte membrane and a plurality of cathode electrodes on the other side of the electrolyte membrane, and with the cells connected in series. A structure for connecting anode electrodes on a first surface of the electrolyte membrane and cathode electrodes of a second surface of an electrolyte membrane was disclosed in U. S. Patent Publication Nos. 2003/0180594 and 2003/0198853. The connection structure describes therein effectively connects current collectors in series. However, when one of the cells is damaged, the performance of the whole fuel cell may be reduced.
Generally, in a monopolar type fuel cell stack, conductive plates (separators) make a serial connection between unit cells. However, when the performance of a unit cell is reduced, it is difficult to remove or replace the unit cell.
U.S. Patent Publication No. 2004/0247964 describes an element for detecting a voltage of a unit cell by connecting to unit cells of a fuel cell and an element for bypassing a unit cell that performs at a reduced level. However, as described more fully herein, merely by-passing an underperforming cell reduces the total current density of the fuel cell. In contrast, as described more fully herein, the power density of a fuel cell can be improved by connecting an underperforming unit cell in parallel to adjacent normal unit cells. Therefore, there is a need for a circuit connection control system that can connect a unit cell performing at a reduced level in parallel to normal adjacent unit cells.